Parallel parking assistant system and method thereof

ABSTRACT

A parallel parking assistant system integrated with a vehicle and method thereof are provided, the parking assistant system including a first sensor configured to determine a first distance, a second sensor configured to determine a second distance, and a controller configured to provide commands as a function of the first and second determined distances. The commands include a first command configured to command a steering system to be in a clockwise position while the vehicle is moving in a reverse direction for a first reversing distance, a second command configured to command the steering system to be in a substantially straight position while the vehicle is moving in a reverse direction for a second reversing distance, and a third command configured to command the steering system to be in a counter-clockwise position while the vehicle is a moving in a reverse direction for a third reversing distance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.12/758,218, filed Apr. 12, 2012, entitled “PARALLEL PARKING ASSISTANTSYSTEM AND METHOD THEREOF”

FIELD OF THE INVENTION

The present invention generally relates to a parking assistant systemand method thereof, and more particularly, a parallel parking assistantsystem integrated with a vehicle and a method thereof.

BACKGROUND OF THE INVENTION

Generally, autonomous parallel parking systems require the use ofmultiple distance sensors that are strategically located at variouslocations around a host vehicle body structure, such as a front-sidefascia, a rear-side fascia, a front bumper, and a rear bumper. Thesesensors can collectively measure various displacements between the hostvehicle and adjacent parked vehicles. The controller can use thesevarious displacement measurements to implement algorithms to adjust asteer angle of the host vehicle to allow the host vehicle to back intothe parking space and avoid impacting the adjacent parked vehicles.

These parallel-parking systems can be expensive due to the cost of themultiple sensors and the controller that processes the algorithms.Typically, the parallel-parking system implementation can require theadditional cost of controllable steering (e.g., electric powersteering), controllable brakes, and controllable throttles.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a parallel parkingassistant system integrated with a vehicle that includes a steeringsystem, a brake system, and a throttle system is provided. The parkingassistant system includes a first sensor configured to determine a firstdistance to an object adjacent to a side of the vehicle, a second sensorconfigured to determine a second distance between a forward positionedobject and a rear positioned object that define a parking space, and acontroller in communication with the first and second sensors, whereinthe controller is configured to provide commands to control the steeringsystem, the brake system, and the throttle system of the vehicle as afunction of the first and second determined distances. The commandsinclude a first command configured to command the steering system to bein a clockwise position while the vehicle is moving in a reversedirection for a first reversing distance, a second command configured tocommand the steering system to be in a substantially straight positionwhile the vehicle is moving in a reverse direction for a secondreversing distance, wherein a distance traveled during the first andsecond reversing distances is a function of a length of the vehicle, anda third command configured to command the steering system to be in acounter-clockwise position while the vehicle is a moving in a reversedirection for a third reversing distance, wherein a distance traveledduring the first, second, and third reversing distances is a function ofthe determined first and second distances, a longitudinal displacementof the vehicle during the first, second, and third commands, and alateral displacement of the vehicle during the first, second, and thirdcommands.

According to another aspect of the present invention, a method ofparallel parking a vehicle including a steering system is provided. Themethod includes the steps of determining a first distance between a sideof the vehicle and an object adjacent the side of the vehicle,determining a second distance between a forward positioned object andrear positioned object that define a parking space, rotating thesteering system in a clockwise direction while the vehicle is moving ina reverse direction for a first reversing direction, rotating thesteering system to a substantially straight position while the vehicleis moving in a reverse direction for a second reversing direction,wherein a distance traveled during the first and second reversingdistances is a function of a length of the vehicle, and rotating thesteering system to a counter-clockwise direction while the vehicle ismoving in a reverse direction for a third reversing direction, wherein adistance traveled during the first, second, and third distances is afunction of the determined distance, a longitudinal displacement of thevehicle during the rotating the steering system step, and a lateraldisplacement of the vehicle during the rotating the steering systemstep.

According to yet another aspect of the present invention, a method ofparallel parking a host vehicle is provided that includes the steps ofdetermining a lateral and longitudinal distance of a parking space,determining an offset distance between the host vehicle and an adjacentforward positioned object, implementing a first substantially maximumturning operation while displacing the vehicle a first reversingdistance, implementing a substantially straight operation whiledisplacing the vehicle a second reversing distance, and implementing asecond substantially maximum turning operation while displacing thevehicle a third reversing distance, wherein the first substantiallymaximum turning operation and the second substantially maximum turningoperation are different directions.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a parallel parking assistant systemintegrated with a vehicle, in accordance with one embodiment of thepresent invention;

FIG. 2A is a schematic diagram of a vehicle illustrating an exemplaryvehicle length V_(L) of a round-front vehicle, in accordance with oneembodiment of the present invention;

FIG. 2B is a schematic diagram of a vehicle illustrating an exemplaryvehicle length V_(L) of a flat-front vehicle, in accordance with oneembodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an exemplary path of travelof a vehicle when parallel parking, in accordance with one embodiment ofthe present invention;

FIG. 4 is a schematic diagram illustrating an exemplary path of travelof a vehicle when parallel parking, in accordance with one embodiment ofthe present invention;

FIG. 5 is a schematic diagram illustrating an exemplary path of travelof a vehicle when parallel parking, in accordance with one embodiment ofthe present invention;

FIG. 6 is a schematic diagram illustrating an exemplary path of travelof a vehicle when a steering system of the vehicle is turned to asubstantially locked position in a clockwise direction, in accordancewith one embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating an exemplary path of travelof a vehicle when parallel parking, in accordance with one embodiment ofthe present invention; and

FIG. 8 is a flowchart illustrating a method of parallel parking avehicle, in accordance with one embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

In regards to FIG. 1, a parallel parking assistant system is generallyshown at reference identifier 100. Typically, the parallel parkingassistant system 100 is integrated with a vehicle, which is generallyindicated at reference identifier 102 and/or V_(H), and can include asteering system that is generally indicated at reference identifier 104,a brake system 105, and a throttle system 107. The parallel parkingassistant system 100 can further include a first sensor 106 that isconfigured to determine a first distance to an object adjacent to a sideof the vehicle 102, V_(H) (FIGS. 3-5 and 7), and a second sensor 109configured to determine a second distance between a forward positionedobject and a rear positioned object that define a parking space. Theparallel parking assistant system 100 can also include a controller 108in communication with the first sensor 106 and the second sensor 109,wherein the controller 108 is configured to provide commands to thesteering system 104, the brake system 105, and the throttle system 107of the vehicle 102, V_(H) for steering the vehicle 102, V_(H) as afunction of the determined first and second distances.

The commands provided by the controller 108 can include a first commandconfigured to command the steering system 104 to be in a clockwiseposition while the vehicle 102, V_(H) is moving in a reverse directionfor a first reversing distance. The commands provided by the controller108 can further include a second command configured to command thesteering system 104 to be in a substantially straight position while thevehicle 102, V_(H) is moving in a reverse direction for a secondreversing distance, wherein a distance traveled during the first andsecond reversing distances is a function of a length of the vehicle(V_(L)) 102. Also, a third command can be configured to command thesteering system 104 to be in a counter-clockwise position while thevehicle 102, V_(H) is moving in a reverse direction for a thirdreversing distance, wherein a distance traveled during the first,second, and third reversing distances is a function of the determineddistances, a longitudinal displacement of the vehicle 102, V_(H) duringthe first, second, and third commands, and a lateral displacement of thevehicle 102, V_(H) during the first, second, and third commands, as setforth in greater detail herein.

According to one embodiment, the parallel parking assistant system 100can use the sensor 106 that is a short-range distance sensor. The sensor106 can be positioned on a passenger side of the vehicle 102, V_(H),such that the parallel parking assistant system 100 is configured toparallel park the vehicle 102, V_(H) with respect to the passenger sideof the vehicle 102, V_(H) as a function of one or more outputs of thesensor 106. Typically, the sensor 106 can be located on the passengerside of the vehicle 102, V_(H) in order to measure the offset distanceX_(OFFSET) (FIG. 3) between the vehicle 102, V_(H) and an adjacentobject (e.g., an adjacently parked vehicle V_(F)). According to oneembodiment, the offset distance X_(OFFSET) can be a minimum distancebetween the vehicle 102, V_(H) and the forward positioned object V_(F),a maximum distance between the vehicle 102, V_(H) and the rearpositioned object V_(F), or an average distance between the vehicle 102,V_(H) and the forward positioned object V_(F) and the vehicle 102, V_(H)and the rear positioned object Y_(R). However, it should be appreciatedby those skilled in the art that other suitable determined, measured, orcalculated distances can be used to determine the offset distanceX_(OFFSET). The parallel parking assistant system 100 can thenaccomplish the parallel parking of the vehicle 102, V_(H) by havingthree (3) turning sequences while the vehicle 102, V_(H) is moving in areverse direction, which can allow for both an autonomous,semi-autonomous, or manual mode, as described in greater detail herein.

For purposes of explanation and not limitation, the parallel parkingassistant system 100 is illustrated and described herein with the sensor106 being located on a passenger side of the vehicle 102, V_(H), suchthat the vehicle 102, V_(H) is parallel parked with respect to thepassenger side. However, it should be appreciated by those skilled inthe art that an additional sensor or the sensor 106 can be located on adriver's side of the vehicle 102, V_(H), such that the parallel parkingassistant system 100 can parallel park the vehicle 102, V_(H) withrespect to a driver's side of the vehicle 102, V_(H). By way ofexplanation and not limitation, the sensor 106, 109 can be at least oneof an ultrasonic sensor, a radar sensor, a lidar sensor, a camera, thelike, or a combination thereof.

The controller 108 can be configured to be both, but only one at a time,in an autonomous mode, in a semi-autonomous mode, or in a manual modeaccording to one embodiment. Typically, the controller 108 can providethe commands to the steering system 104 when the controller 108 is inthe autonomous mode. When the controller 108 is in the manual mode, thecontroller 108 can provide the commands to a user of the vehicle 102,V_(H), such that the user can control a steering system 104 of thevehicle 102, V_(H) based upon the provided commands. In such a manualmode, the controller 108 can provide the commands by an audioenunciation, a visual output (e.g., one or more indicator lights, anoutput on a screen, such as, but not limited to, a navigation systemscreen), the like, or a combination thereof. The semi-autonomous modecan incorporate a portion of functions of the autonomous mode and aportion of functions of the manual mode. A configuration to switchbetween the autonomous mode, the semi-autonomous mode, and the manualmode can be configured by a manufacturer of the vehicle 102, V_(H), amanufacturer of the parallel parking assistant system 100 and/or othercomponents of the vehicle 102, V_(H), a dealer or seller of the vehicle102, V_(H), a user of the vehicle 102, V_(H), or a combination thereof.

The steering system 104 can include a steering wheel 110 operablyconnected to a front axle 112, and the front axle 112 can be operablyconnected to one or more wheels 114, according to one embodiment.Typically, when the steering system 104 is turned to a clockwisedirection, the steering wheel 110 is activated or turned in a clockwisedirection so that the one or more wheels 114 operably connected to thesteering wheel 110 would direct the vehicle 102, V_(H) in a clockwisedirection when the vehicle 102, V_(H) is traveling in a forwarddirection with respect to a normal operational position of the vehicle102, V_(H). Similarly, when the steering system 104 is turned to asubstantially straight or turned to a counter-clockwise direction, thesteering wheel 110 is activated or turned in a substantially straight orcounter-clockwise direction, so that the one or more wheels 114 operablyconnected to the steering wheel 110 would direct the vehicle 102, V_(H)in a substantially straight or counter-clockwise direction when thevehicle 102, V_(H) is traveling in a forward direction with respect to anormal operational position of the vehicle 102, V_(H), respectively.

According to one embodiment, the sensor 106 can be positioned on a rearportion of the passenger side of the vehicle 102, V_(H) (FIG. 1), suchthat the controller 108 can be configured to provide the first, second,and third commands as a function of a lateral displacement between therear portion of the passenger side of the vehicle 102, V_(H) and one ormore objects adjacent thereto (e.g., a forward and rear parked vehicleV_(F), V_(R)). The controller 108 can also be configured to provide acommand prior to the first command, wherein the prior command can beconfigured to command the steering system 104 to be in a substantiallystraight position, while the vehicle 102, V_(H) is moving in a forwarddirection from a rear positioned adjacent object towards a forwardpositioned adjacent object, such that the forward positioned adjacentobject and rear positioned object define a parking space.

In such an embodiment, the second sensor 109 can be, but is not limitedto, a wheel speed sensor configured to determine the distance betweenthe forward positioned object (e.g., a forward parked vehicle V_(F)) andthe rear positioned object (e.g., a rear parked vehicle V_(R)). Thus,the first sensor 106 can be used to measure an offset distance(X_(OFFSET)) to determine if a parking space exists, and the secondsensor 109 can be used to measure a length of a parking space. However,it should be appreciated by those skilled in the art that the forwardpositioned object, the rear positioned object, or a combination thereof,can be objects other than vehicles, and that a description herein as toother parked vehicles is for purposes of explanation and not limitation.Additionally or alternatively, the second sensor 109 can be used tomeasure the first reversing distance, the second reversing distance, thethird reversing distance, the like, or a combination thereof.

In regards to FIGS. 1-2B, these figures illustrate exemplary dimensionsthat can be measured or can be known values within the parallel parkingassistant system 100. According to one embodiment, the sensor 106 islocated on the passenger side of the vehicle 102, V_(H), wherein adistance Y_(S) is the distance between a most rear portion of thevehicle 102, V_(H) and the sensor 106 (FIG. 1). With respect to FIG. 2A,the vehicle 102 (or host vehicle V_(H)) length V_(L) can be determinedby the distance between an approximate center point of a rear axle 116to approximately a front bumper 118. Alternatively, in a flat-frontvehicle 102, V_(H) type (FIG. 2B), the vehicle 102, V_(H) length V_(L)can be from an approximate center point of the rear axle 116 toapproximately a front corner of the vehicle 102, V_(H).

In regards to FIG. 3, a width of the vehicle 102, V_(H) is representedby X_(WIDTH), and a displacement between the vehicle 102, V_(H) and afront parked vehicle V_(F) is represented by X_(OFFSET). Typically, thedisplacement value X_(OFFSET) is measured by the sensor 106. Alongitudinal value Y_(SPACE) of an available parking space, which istypically defined by the space between the front parked vehicle V_(F)and a rear parked vehicle V_(R) can be determined. The longitudinalvalue Y_(SPACE) can be measured by a second sensor 109, such as, but notlimited to, a wheel speed sensor. A total lateral displacement resultingfrom a completed parallel park maneuver can be represented by X_(TOTAL),while the total longitudinal displacement resulting from a completedparallel park maneuver can be represented by Y_(TOTAL). Also, a totaldistance traveled by the host vehicle 102, V_(H) to complete a parallelpark maneuver can be represented by L_(TOTAL).

Typically, to conduct a parallel parking procedure, the displacementX_(OFFSET) between the host vehicle 102, V_(H) and a front park vehicleV_(F) can be limited within the bounds of:0<X _(MIN) <X _(OFFSET) <X _(MAX)  Eq. 1

Typically, variables X_(MAX) and X_(MIN) are selected based uponallowing satisfaction of geometric approximation of turning procedures.The variable X_(MIN) can be limited by the distance to an adjacentobject (e.g., the front parked vehicle V_(F)), since the vehicle 102,V_(H) cannot be located in the exact same position as any part of theadjacent objects (e.g., parked vehicle's V_(F), V_(R)), and thus, thevariable X_(MIN) has a value of greater than zero. According to oneembodiment, the variable X_(OFFSET) has a value that is equal to orgreater than approximately six inches (6 in), and the variable ofX_(MAX) can have a value suitable to ensure the vehicle 102, V_(H) isapproximately one driving lane over from the adjacent objects (e.g.,parked vehicles V_(F), V_(R)). However, it should be appreciated bythose skilled in the art that the variable X_(MAX) can have any value,but may be limited by other factors, such as, but not limited to,typical dimensions of roadways, a turning radius of the vehicle 102,V_(H), an error or tolerance of a travel path shape or distance, thelike, or a combination hereof. Additionally or alternatively, the valueof the displacement X_(OFFSET) can vary, such that the value of thedisplacement X_(OFFSET) can be, but is not limited to, a combination ofvalues or an average of values.

A total lateral displacement X_(TOTAL) can result in an edge alignmentof the vehicle 102, V_(H) and a front parked vehicle V_(F), which can berepresented by:X _(TOTAL) =X _(OFFSET) +X _(WIDTH)  Eq. 2

The total longitudinal displacement Y_(TOTAL) for a parallel parkingoperation can be determined to be able to fit into an allowable parkingspace as represented by the following equation:Y _(TOTAL) <Y _(SPACE)  Eq. 3

With respect to FIG. 4, in an embodiment that is utilizing a three (3)steering system 104 turning operation (e.g., two (2) opposing turningbackward maneuvers connected by a substantially straight or linearbacking maneuver), various displacement values can be determined.Typically, the first turning backing maneuver is where the steeringsystem 104 is substantially locked in a clockwise direction, and thelinear backing maneuver can be with the steering system 104 issubstantially straight (e.g., θ_(STEERING)=0°). Further, the secondturning backing operation can be where the steering system 104 issubstantially locked in a counter-clockwise direction. According to oneembodiment, the steering system 104 is locked when the steering wheel110 is turned a maximum position in either direction.

The first turning backing maneuver in combination with the substantiallystraight backing maneuver can be configured so that a front end of thevehicle 102, V_(H) does not contact the front parked vehicle V_(F) whenthe vehicle 102, V_(H) is conducting the second turning backingmaneuver, according to one embodiment. Various longitudinal displacementvalues of the vehicle 102, V_(H) during the three (3) steering system104 turning operation that can be determined are a displacementresulting from a first turning backing maneuver Y_(T1), a displacementresulting from the substantially straight backing maneuver Y_(L), and adisplacement resulting from a second turning backing maneuver Y_(T2). Atotal longitudinal displacement Y_(TOTAL) can be calculated utilizingthe following equation:Y _(TOTAL) =Y _(T1) +Y _(L) +Y _(T2)  Eq. 4

Additionally, the vehicle 102, V_(H) can have a lateral displacementwhen utilizing the three (3) steering system 104 turning operation.Various lateral displacement values that can be determined include adisplacement resulting from first turning backing maneuver X_(T1), adisplacement resulting from a substantially straight backing maneuverX_(L), and a displacement resulting from a second turning backingmaneuver X_(T2). A total lateral displacement X_(TOTAL) can becalculated utilizing the following equation:X _(TOTAL) =X _(T1) +X _(L) +X _(T2)  Eq. 5

In regards to FIGS. 5 and 6, exemplary geometry characteristics of aparallel parking maneuver are shown. Typically, a motion of one or morerear wheels 114 is approximated by a circle when substantially lockingthe steering system 104 while performing a backing maneuver (FIG. 6).However, front wheels 114 of the vehicle 102, V_(H) typically do nothave the same turning radius as rear wheels 114, and the rear axis 116can point to a center of an imaginary circle, such that a frame ofreference is a center point of the rear axle 116 (e.g., a motiontraveled). Circle characteristics with respect to the rear axle 116 ofthe vehicle 102, V_(H) can include a radius of an exemplary turningcircle R, angle displacement by a turn θ, and a length of arc traveledby the angle displacement L. Typically, for a small angle displacementθ, the circle approximation is nearly correct. This condition can beensured by satisfaction within geometric bounds of the parallel parkingprocedure. According to one embodiment, testing can be conducted withthe vehicle 102, V_(H) to obtain data and provide table look up valuesof “R” and “L” variables for various circumstances.

Longitudinal displacement geometric relationships (FIG. 5) can becalculated by the following equations:Y _(T1) =R _(T1) sin(θ_(T1))  Eq. 6Y _(L) =L _(L) cos(θ_(T1))  Eq. 7Y _(T2) =R _(T2) sin(θ_(T2))  Eq. 8

Lateral displacement geometric relationships (FIG. 5) can be calculatedusing the following equations:X _(T1) =R _(T1) −R _(T1) cos(θ_(T1))=R _(T1)[1−cos(θ_(T1))]  Eq. 9X _(L) =L _(L) sin(θ_(T1))  Eq. 10X _(T2) =R _(T2) −R _(T2) cos(θ_(T2))=R _(T2)[1−cos(θ_(T2))]  Eq. 11

The vehicle 102, V_(H) motion displacement along a circular arc can havevarious characteristics. A distance traveled from a first turningbacking maneuver L_(T1) can be calculated using the following equation:L _(T1) =R _(T1)θ_(T1), (wherein θ_(T1) is specified in radians)

A distance traveled from a substantially straight backing maneuver L_(L)can be determined. Also, a distance traveled from a second turningbacking maneuver L_(T2) can be calculated by the following equation:L _(T2) =R _(T2)θ_(T2) (wherein θ_(T2) is specified in radians)  Eq. 13

Thus, a total distance traveled can be represented by L_(TOTAL), andcalculated by the following equation:L _(TOTAL) =L _(T1) +L _(L) +L _(T2)  Eq. 14

On-board vehicle motion sensors such as, but not limited to, the secondsensor 109 (e.g., wheel speed sensors), can provide actual measurementsof motions traveled parameters (e.g., L_(T1), L_(L), L_(T2)) andapproximately translated to a rear axle coordinate frame, according toone embodiment. Measured parameters can include a measured distancetraveled from a first turning backing maneuver L_(T1M), a measureddistance traveled from a substantially linear backing maneuver L_(LM),and a measured distance traveled from a second turning back maneuverL_(T2M).

According to one embodiment, opposing circular backing maneuvercharacteristics can be substantially identical. In such an embodiment,the host vehicle 102, V_(H) can have backing dynamic motion parametercharacteristics R, S, and θ that are substantially identical when thesteering system 104 is substantially locked in either the clockwise orcounter-clockwise position. When assuming the turning characteristicsare substantially identical, then the various backing dynamic motionparameter characteristics can be calculated by the following equations:θ_(T)=θ_(T1)=θ_(T2)  Eq. 15R _(T) =R _(T1) =R _(T2)  Eq. 16L _(T) =L _(T1) =L _(T2)  Eq. 17

Substitutions of Equations 15 and 16 into Equations 4-11, andsimplification thereof yields:Y _(TOTAL)=2Y _(T) +Y _(L)=2R _(T) sin(θ_(T))+L _(L) cos(θ_(T))  Eq. 18X _(TOTAL)=2X _(T) +X _(L)=2R _(T)[1−cos(θ_(T))]+L _(L) sin(θ_(T))

According to one embodiment, the longitudinal and lateral displacementsof the vehicle 102, V_(H) doing the first turning backing maneuverY_(T1), X_(T1), and the substantially straight backing maneuver Y_(L),X_(L), are determined to ensure vehicle's 102, V_(H) front bumper 118does not contact the front parked vehicles V_(F) rear bumper whenperforming the second turning backing maneuver (FIG. 4). In such anembodiment, a length L_(V) of the vehicle 102, V_(H) can besubstantially equal to the combined longitudinal components of the firstbacking maneuver Y_(T1) and the substantially straight backing maneuverY_(L), as represented by the following equation:L _(V) =Y _(T1) +Y _(L)  Eq. 20

Substitution of Equations 6 and 7 with Equations 15 and 16 into Equation20 yields:L _(V) =R _(T) sin(θ_(T))+L _(L) cos(θ_(T))  Eq. 21

Solving Equation 21 for L_(L) is represented by the following equation:

$\begin{matrix}{L_{L} = {\frac{L_{V}}{\cos\left( \theta_{T} \right)} - {R_{T}{\tan\left( \theta_{T} \right)}}}} & {{Eq}.\mspace{14mu} 22}\end{matrix}$

Total linear displacement X_(TOTAL) to accomplish a parallel parkingmaneuver can be calculated by substituting Equations 2 and 22 intoEquation 19, which yields the following equation:

$\begin{matrix}{{X_{OFFSET} + X_{WIDTH}} = {{2{R_{T}\left\lbrack {1 - {\cos\left( \theta_{T} \right)}} \right\rbrack}} + {\left\lbrack {\frac{L_{V}}{\cos\left( \theta_{T} \right)} - {R_{T}{\tan\left( \theta_{T} \right)}}} \right\rbrack{\sin\left( \theta_{T} \right)}}}} & {{Eq}.\mspace{14mu} 23}\end{matrix}$

Further simplification of Equation 23 yields:X _(OFFSET) +X _(WIDTH) =R _(T)[2−2 cos(θ_(T))−sin(θ_(T))tan(θ_(T))]+L_(V) tan(θ_(T))  Eq. 24

Solving for a subtended angle displaced by a turn θ_(T) from Equation24, wherein the parameters set (X_(OFFSET), X_(WIDTH), R_(T), L_(V)) aretypically known values, yield the following closed-form geometricequation:θ_(T) =f(X _(OFFSET) ,X _(WIDTH) ,R _(T) ,L _(V))  Eq. 25

Typically, θ_(T) of Equation 24 is solved using numerical analysistechniques. According to one embodiment, the values of X_(OFFSET),X_(WIDTH), R_(T), and L_(V) can be known values because these values aredetermined using the first sensor 106 and/or the second sensor 109, theyare measureable parameters of the vehicle 102, V_(H), the like, or acombination thereof.

Total longitudinal displacement Y_(TOTAL) required for a parallelparking maneuver can be represented by substituting Equation 22 intoEquation 18, which yields the following equation:

$\begin{matrix}{Y_{TOTAL} = {{2R_{T}{\sin\left( \theta_{T} \right)}} + {\left\lbrack {\frac{L_{V}}{\cos\left( \theta_{T} \right)} - {R_{T}{\tan\left( \theta_{T} \right)}}} \right\rbrack{\cos\left( \theta_{T} \right)}}}} & {{Eq}.\mspace{14mu} 26}\end{matrix}$

Further simplification of Equation 26 yields the following equation:Y _(TOTAL) =R _(T) sin(θ_(T))+L _(V)   Eq. 27

Knowing θ_(T) by utilizing Equation 25, then Equation 27 can yield thefollowing closed-form geometric equation:Y _(TOTAL) =R _(T) sin(f(X _(OFFSET) ,X _(WIDTH) ,R _(T) ,L _(V)))+L_(V)  Eq. 28

Typically, the parameters set X_(OFFSET), X_(WIDTH), R_(T), and L_(V)are known values, wherein, the values of X_(OFFSET), X_(WIDTH), R_(T),and L_(V) can be known values because these values are determined usingthe first sensor 106 and/or the second sensor 109, they are measureableparameters of the vehicle 102, V_(H), the like, or a combinationthereof. According to one embodiment, the potential parking space issufficiently long enough to accommodate the parallel parking maneuver ifEquation 28 satisfies Equation 3.

With respect to FIG. 7, known vehicle system parameters can includeX_(WIDTH), R_(T), L_(V), Y_(S), X_(MAX), and X_(MIN), according to oneembodiment. When a user of the vehicle 102, V_(H) desires to parallelpark, the user can stop the vehicle 102, V_(H) at Position 1 and enablethe parallel parking assistant system 100. The vehicle 102, V_(H) canthen move forward slowly (autonomous or semi-autonomously) past the rearadjacent object (e.g., the rear parked vehicle V_(R)), and potentialparking space, until the sensor 106 detects the forward adjacent object(e.g., the forward parked vehicle V_(F)). The vehicle 102, V_(H) motionwill stop at Position 2 when the vehicle 102, V_(H) rear bumper isaligned with the forward parked vehicle V_(F) rear bumper. The length ofthe parking space Y_(SPACE) can be measured from a vehicle 102, V_(H)motion sensor (e.g., a wheel speed sensor). An offset distanceX_(OFFSET) can be measured from the sensor 106, and longitudinaldistance Y→TOTAL can be calculated from Equation 28.

The parallel parking assistant system 100 can inform a driver of thevehicle 102, V_(H) whether the potential parking space is suitable forparallel parking operation when the conditions Equations 1 and 2 aremet. If the parallel parking space is suitable, the user of the vehicle102, V_(H) can engage the parallel parking assisting system 100 to allowthe vehicle 102, V_(H) to move backwards slowly (autonomously orsemi-autonomously) to perform the following three (3) backing maneuverssequences.

The first backing steering maneuver can include the steering system 104being substantially in clockwise locking position. The vehicle 102,V_(H) moves backwards until the following transitional conditions aremet:L _(T1M) =L _(T1)  Eq. 29

Using Equation 12 with Equations 15 and 16 yields:L _(T1M) =R _(T)θ_(T) (wherein θ_(T) is translated into radians)  Eq. 30

Using Equation 25, Equation 30 then becomes:L _(T1M) =R _(T) f(X _(OFFSET) ,X _(WIDTH) ,R _(T) ,L _(V))  Eq. 31

The substantially linear or straight backing maneuver can be when thesteering system 104 is substantially straight (e.g., θ_(STEERING)=0°),wherein the vehicle 102, V_(H) moves backward until the followingtransitional conditions are met:L _(LM) =L _(L)  Eq. 32

Using Equation 22 with Equation 32 yields:

$\begin{matrix}{L_{LM} = {\frac{L_{V}}{\cos\left( \theta_{T} \right)} - {R_{T}{\tan\left( \theta_{T} \right)}}}} & {{Eq}.\mspace{14mu} 33}\end{matrix}$

Using Equation 25, then Equation 33 becomes:

$\begin{matrix}{L_{LM} = {\frac{L_{V}}{\cos\left( {f\left( {X_{OFFSET},X_{WIDTH},R_{T},L_{V}} \right)} \right)} - {R_{T}{\tan\left( {f\left( {X_{OFFSET},X_{WIDTH},R_{T},L_{V}} \right)} \right)}}}} & {{Eq}.\mspace{14mu} 34}\end{matrix}$

The second backing steering maneuver can be accomplished when thesteering system 104 is substantially locked in a counter-clockwiseposition, and the vehicle 102, V_(H) moves backwards until the followingstopping condition is met:L _(T2M) =L _(T2)  Eq. 35

Using Equation 12 with Equations 15 and 16 yields:L _(T2M) =R _(T)θ_(T) (wherein θ_(T) is translated into radians)  Eq. 36

Using Equation 25, then Equation 26 becomes:L _(T2M) =R _(T) f(X _(OFFSET) ,X _(WIDTH) ,R _(T) ,L _(V))  Eq. 37

The vehicle 102, V_(H) can then be positioned between the two parkedvehicles V_(F), V_(R), or adjacent objects that define the parkingspace.

With respect to FIGS. 1-8, a method of parallel parking the vehicle 102,V_(H) that includes the steering system 104 is generally shown in FIG. 8at reference identifier 200. The method 200 starts at step 202, and canproceed to step 204, wherein a longitudinal space between a frontadjacent object (e.g., a forward positioned object, such as, but notlimited to, a front parked vehicle V_(F)) and a rear adjacent object(e.g., a rear positioned object, such as, but not limited to, a rearparked vehicle V_(R)) is measured, according to one embodiment. Themethod 200 then proceeds to step 206, wherein a longitudinal parkingdistance is calculated.

At decision step 208, it is determined if the parking space isadequately long enough (e.g., Y_(TOTAL) is less than Y_(SPACE)). If itis determined at decision step 208 that the parking space is notadequately long enough, then the method 200 proceeds to step 216,wherein the method 200 ends. However, if it is determined at decisionstep 208 that the parking space is adequately long enough, the method200 proceeds to step 210. At step 210, the first turning operation isimplemented. Typically, the first turning operation includes turning thesteering system 104 in a counter-clockwise direction, while the vehicle102, V_(H) travels a first reversing distance. At step 212 asubstantially straight operation is implemented, and at step 214, asecond turning operation is implemented. Typically, the second turningoperation includes turning the steering system 104 in a clockwisedirection, while the vehicle 102, V_(H) travels a third reversingdistance. The method 200 then ends at step 216.

Advantageously, the parallel parking assistant system 100 and method 200can be utilized to park a vehicle 102, V_(H) within a parking spacedefined by two objects, such as two parked vehicles V_(F), V_(R),wherein the parallel parking assistant system 100 can be an autonomousmode, a semi-autonomous mode, or a manual mode. The parallel parkingassistant system 100 provides assistance to a driver of the vehicle 102,V_(H) to parallel park the vehicle 102, V_(H), while requiring minimalhardware by utilizing a single sensor 106, which can reduce a cost ofmanufacturing. It should be appreciated by those skilled in the art thatthe parallel parking assistant system 100 and method 200 can haveadditional or alternative advantages. It should further be appreciatedby those skilled in the art that the above-described components of theparallel parking assistant system 100 and steps of the method 200 can becombined in additional or alternative ways.

Modifications of the invention will occur to those skilled in the artand to those who make or use the invention. Therefore, it is understoodthat the embodiments shown in the drawings and described above aremerely for illustrative purposes and not intended to limit the scope ofthe invention, which is defined by the following claims as interpretedaccording to the principles of patent law, including the doctrine ofequivalents.

The invention claimed is:
 1. A parallel parking assistant system integrated with a vehicle that comprises a steering system, a brake system, and a throttle system, said parking assistant system comprising: a first sensor configured to determine a first distance to an object adjacent to a side of the vehicle; and a second sensor configured to determine a second distance between a forward positioned object and a rear positioned object that define a parking space; a controller in communication with said first and second sensors, wherein said controller is configured to provide commands to control the steering system of the vehicle as a function of said determined first and second distances, said provided commands comprise: a first command configured to command the steering system to be in a clockwise position while the vehicle is moving in a reverse direction for a first reversing distance; a second command configured to command the steering system to be in a substantially straight position while the vehicle is moving in a reverse direction for a second reversing distance, wherein a distance traveled during said first and second reversing distances is a function of a length of the vehicle; and a third command configured to command the steering system to be in a counter-clockwise position while the vehicle is moving in a reverse direction for a third reversing distance, wherein a distance traveled during said first, second, and third reversing distances is a function of said determined first and second distances, a longitudinal displacement of the vehicle during said first, second, and third commands, and a lateral displacement of the vehicle during said first, second, and third commands.
 2. The parallel parking assistant system of claim 1, wherein said longitudinal and lateral displacement of the vehicle during said first, second, and third commands is a function of a length of a parking space (Y_(SPACE)), an offset distance between the vehicle and a forward positioned object (X_(OFFSET)), and a width of the vehicle (X_(WIDTH)).
 3. The parallel parking assistant system of claim 1, wherein said sensor is at least one of ultrasonic, radar, lidar, and a camera.
 4. The parallel parking assistant system of claim 1, wherein said controller is configured to be all, but only one at a time, in a manual mode, an autonomous mode, and a semi-autonomous mode.
 5. The parallel parking assistant system of claim 4, wherein said controller provides said commands to the steering system, the brake system, and the throttle system, when said controller is in said autonomous mode, and provides said commands to a user of the vehicle, who then controls the steering system, the brake system, and the throttle system, based upon said provided commands when said controller is in said manual mode.
 6. The parallel parking assistant system of claim 1, wherein said first sensor is positioned on a rear portion of a passenger side of the vehicle, such that said controller is configured to provide said first command as a function of a lateral displacement between said rear portion of said passenger side of the vehicle and said object adjacent thereto.
 7. The parallel parking assistant system of claim 1, wherein said controller is further configured to provide a command prior to said first command that is configured to command the steering system to be in a substantially straight position while the vehicle is moving in a forward direction from rear positioned adjacent object towards a forward positioned adjacent object, such that said forward positioned adjacent object and a rear positioned adjacent object define a parking space and a longitudinal distance between said forward positioned adjacent object and said rear positioned adjacent object is determined by said second sensor. 